Direct current relay



Oct. 18, 1938. p, M, -rz 2,133,511

DIRECT CURRENT RELAY Filed Oct. 50, 1936 RELAY L/NE' INVENTOR,

RALPH M. HE/NTZ.

A TTORNE YS.

Patented Oct. 18, 1938 UNITED STATES PATENT OFFICE DIRECT CURRENT RELAY Ware Application October 30, 1936, Serial No. 108,431

Claims.

My invention relates to direct current relays, and particularly to a slow closing, quick releasing relay.

Among the objects of my invention are: To provide a relay adapted to close slowly a secondary circuit upon energization of a primary circult; to provide a relay adapted to release instantaneously upon the cessation of current flow therethrough; to provide an electrical damper opposing the closing of a relay while aiding the opening thereof; to provide means for absorbing the energy latent in the magnetic circuit of a relay at the cessation of current flow through the relay windings; and to provide such a unilateral damper which may be easily and economically constructed and shall be.free from the necessity for frequent attention.

My invention possesses numerous other objects and features of advantage, some of which, together with the foregoing, will be set forth in the following description of specific apparatus embodying and utilizing my novel method. It is therefore to be understood that my method is applicable to other apparatus, and that I do not limit myself, in any way, to the apparatus of the present application, as I may adopt various other apparatus embodiments, utilizing the method, within the .scope of the appended claims.

Briefly as to apparatus, my invention comprises a coil linking the magnetic circuit offa relay, bridged by an energy-storing condenser, and so arranged that the coil is short-circuited by a contact fixed to the movable element of the relay when the relay is closed.

The drawing shows my invention schematically,

connected for operation between a controlling and a controlled circuit.

Various mechanical -means have been designed to cushion the action of relays including springs, resilient cushions, pneumatic and hydraulic dash pots, and various other embodiments. All of them are open to objections; the dash pot embodiments are commonly sluggish and irregular in their actions, and can be closely controlled only with considerable difficulty; cushions and springs tend toacquire permanent sets, and accurate control of their action is not readily obtained. These forms all require complicated mechanism to deal with situations wherein it is desirable to operate slowly in one direction, and rapidly in the other.

In addition, there is an objection common to all in that they attempt to deal with what is essentially an electro-magnetic problem by mechanical rather than electro-magnetic means.

In the instant case, the closing of the relay is electrically cushioned and retarded, while thecushioning circuit is modified when the relay is closed to accelerate the opening. The more detailed operation may be better understood by reference to the drawing.

In the figure, a relay comprising a U-shaped magnet core I and a movable pole piece 2 adapted to close the open end of the U is shown schematically,

Current flowing in relay lines 4 and through coils 5 and I5 will energize the magnet core I and cause pole piece 2 to rotate about a pivot I so positioned that a certain degree of rotation will permit the pole piece to make contact with ends 8 and 9 of magnet I and form a closed path of high permeability. Pole piece 2 carries a contact arm III which, when pole piece 2 is touching magnet arms 8 and 9, will engage a stationary contact II and close a circuit to be controlled through a line I2 connected to pole piece 2 and a line I4 connected to stationary contact II. The engagement of the pole piece and magnet is partially restrained by a suitably located spring I5 .held in tension between a supporting member I6 and the pole piece 2.

A more accurately determinable cushioning effect is provided by a coil I I, wound about leg 9 in the same direction as coil 5, and shunted by a condenser I9. The lines of force in magnet core I build up'a counter electro-magnetic force in coil I! which charges condenser I9, and by providing proper capacity in the condenser, any desired amount of energy may be abstracted from the magnetic circuit, with consequent delay in closing contacts III and II. When the pole piece 2 is in contact with arms 8 and 9, an auxiliary contact arm 20, carried by an insulating block 2| fixed upon the end of said pole piece opposite pivot I, engages stationary contacts 22 and 24 connected across coil I1 and condenser I9, shortcircuiting the said coil I'I.

As a consequence of this short circuit, when current ceases to flow in lines 4, a low resistance path is provided through which the changing flux may cause a current to flow, rapidly absorbing the energy stored in. the -'magnetic field and permitting spring I5 to withdraw pole piece 2 and open contacts III and II more quickly than would otherwise be possible. Arcing at terminals 24 and 22 as auxiliary contact arm 20 disconnects is restrained by condenser I9, which willabsorb any energy remaining in the magnetic field. Reducing the resistance of the coil will permit reducing the opening time still further.

I have thus provided a simple electrical method for retarding the closing and accelerating the opening of a relay which requires very little apparatus, is free from necessity of frequent attention, may be accurately adjusted, and will operate smoothly and regularly.

Various modifications will suggest themselves to those skilled in the art. The form of the magnet and pole piece, and the arrangement of the contacts, are all matters of mechanical skill, and may be freely changed while still adhering to the spirit of the claims. The spring arrangement i5 is purely conventional, and any corresponding means of holding the pole piece away from the magnet when no current is flowing in the relay line is deemed a full equivalent.

I claim:

1. In combination with a D. C. relay energizing circuit, a relay comprising an electro'magnet having a core and a winding thereon connected to said circuit, a pole piece engageable with said core when said winding is energized, means operated by movement of said pole piece for completing a circuit to be controlled, a coil linking said magnet core, a condenser bridging said coil, and contacting means fixed to and insulated from said pole piece for short-circuiting said coil in a desired position as said pole piece is moved.

2. In combination with a D. C. relay energizing circuit, a relay comprising an electro-magformed about said core, a condenser shunting said coil, a contact arm fixed to and insulated from said pole piece, and a contact terminal connected to each end of said coil, each positioned to engage said contact arm when said winding is energized.

3. In combination with a D. C. relay energizing circuit, a relay comprising an electro-magnet having a core and a winding thereon connected to said circuit, a pivotally mounted pole piece so positioned as to engage said core when magnetized, means forrestraining said pole piece from such engagement when the said winding is not energized, a coil linking said core and terminated by stationary contacts, a condenser shunted across said coil, a contact arm insulated from and fixed to said pole piece, said contacts being positioned to engage said contact arm when said pole piece is engagedwith said core, a circuit contact fixed to said pole piece, and a second circuit contact positioned to cooperate with said first circuit contact when said pole piece is engaged by said magnet whereby an external circuit may be closed.

4. The combination with a relay having a core, a relay control winding and a pole piece movable in accordance with direct current energization of said winding, of a coil linking said core, a condenser bridged across said coil, and means actuated by movement of said pole piece for shorting and opening said coil and condenser in accordance with the position of said pole piece.

5. The combination as recited in claim 4, wherein the coil and condenser are shorted when the relay control winding is energized, and open when the winding is de-energized.

RALPH M. HEINTZ. 

